1. Field of the Invention
This invention is in the field of fluid heating apparatus such as a water heater for household and other uses.
2. Description of the Prior Art
Prior art systems for heating fluid have various combinations of thermostatic switches and heating elements to provide adequate supply on demand together with a minimum of energy consumption. In hot water heaters, for example, multiple heating elements and thermostatic switch devices have been used. However, due to the condtradictory objectives of providing hot water on demand and economizing on heating energy during periods of non-use, or low-use, such efforts have been compromises which have not been entirely satisfactory.